Regulation of furnace electrodes



June 24, 1930. G. KELLER 1,766,648.

l REGULATION 0i FURNACE ELECTRODES Filed Sept. 50, 1926 wie@ @gi/M6 Patented June 24, 1930 UNITED STATES PATENT ori-ICE GOTTLIEB KELLER, BROWN .'BOVERI SWITZERLAND F BRUGG, SWITZRLAND, ASSIGNOR T0 AKTIENGESELLSCHAFT & CIE., OF BADEN, SWITZERLAND, A JOINT-STOCK COMPANY OF REGULATION 0F FURNACE ELECTRODES Application led September 30, 1926, Serial No. 138,745, and in Germany October 16, 1925.

This invention pertains to the construction and operation of electric furnaces and has to do particularly withv regulation of the Y feed of the electrodes.

A general object of the invention is to increase the certainty and accuracy of the control or regulation of the feed of the electrodes.

Another object is the simplification of the electrode adjusting and regulating mechamsm. A

A specific objectV is the provision of a method and apparatus for regulating the feed of the electrodes, which afford desirable safeguards against over-adjustment.

Another specific object is the provision of a method and apparatus whereby` the feed of the electrodes may be controlled automatically from the load of the furnace without danger of over-adjustment.

Another object is the provision of a method and "pparatus whereby the feed of the electrodes may be controlled automatically with accuracy, irrespective of the variations in weight resulting from their wearing away in use. Other and further objects will be pointed out or indicated hereinafter, or will be apparent to one skilled in the' art upon an understanding of the invention or its employment in practice.

For the pur ose of illustrating the invention general y, I disclose herein certain arrangements and apparatus wherein it may be embodied and practiced, but it is to be understood that these examples are not to be accorded any interpretation having the effect of limiting the claims short of the true and most comprehensive scope ofthe invention in the art.

In thepdrawing forming a part of this.

:a il

tages, but heretofore has involved certain dificulties in the direction of accurate control andv regulation, particularly with regard to over-adjustment. Of the hydraulic operating mechanisms, those employing a single acting power cylinder, whereby the electrode is raised by hydraulic pressure and lowered by gravity, possess certain advantages in the direction of simplicity and economy over the type in which a double acting 60 power` cylinder is employed. The automatic regulation of feed of the electrode in the type wherein it is lowered by gravity has involved inaccuracies, however, due to the fact that the weight of the electrode gradually decreases incident to operat-ion of the furnace, with a resulting tendency for the rate of feed to decrease as the` weight of the electrode decreases. Consequently, automatic regulation between the times when the electrode is of maximum length and weight and when it is of minimum length and weight has involved complications necessary to avoid overrunning under the conditions first mentioned and insufficient feed under the lastmcntioned conditions. The present invention satisfactorily solves the difficulties presented by these circumstances, in the manner illustrated by the example shown in the accompanying drawing.

Referring to the drawing, let it be understood that the reference numeral 10 designates the furnace and 11 one of the elec trodes which is carried by an arm or holder 12 supported and vertically adjustable on the` guides 14. The electrode is supplied with current from line 15 through a flexible cable connection v16 which accommodates `the vertical adjustment of the electrode.

cThe power cylinder 17 contains the piston 9a 18 which is connected to the arm 12, so that the arm may be moved upwardly on the guides 14 by hydraulic power applied below the piston. The pressure-transmitting liquid is supplied from a suitable accumulator by the pipe 19 to a regulating valve cylinder 20, from which it'is led to the power cylinder 17 through the pipe 21. The regulating valve 22 is adjustable to regu- 10o late the supply of pressure medium from pipe 19 to pipe 21, or the exhaust from pipe 21 to pipe 24. The position of valve 22 1s in turn regulated by an automatic regulator 25 in accordance with the load taken by the electrode, the same being rendered eii'ective on the regulator through the medium flowing through line 21 from valve cylinder 20, and partially closes under pressure 0f fluid lowin in the opposite direction. The valve is esignated by the reference character 28 and has a guide portion 29 and cooperates with a seat 30. 'An adjustable member 31 determines the extent to which the valve 28 may close. The member 31 may be arranged for adjustment by hand, or otherwise.

In operation, when the adjustment of the regulating valve 22 is such` as to admit pressure medium to the power cylinder 17, the control valve 28 opens full so that the hydraulic pressure is rendere -fully efective against the piston 18 in o pos1tion to the weight of the electrode an its holder. Consequently, the lowering of the electrode may be stopped immediately upon action of the regulator 25. When the adjustment of the regulating valve 22 is such as to permit low of pressure medium from power cylinder 17, control valve 28 occupies its partially closed position, thus throttling the flow of pressure medium from the ower cylinder. In this manner a certain ack pressure is produced in the cylinder from the weight of the electrode and its traveling support, which back ressure retards the descent of the electro e, the retardation being proportional to the eiective weight imposed by the electrode and its traveling support upon the piston 18. As a consequence, it is not necessary to counterbalance the electrode and its carrier, and the regulation of the downward feed of the electrode by the regulating valve may be accomplished with greater uniformity and accuracy and more closely in accordance with load variations on the furnace than is possible when the weight of the electrode and its carrying frame is permitted to exercise a more variable effect on the rate at which the pressure medium is exhausted. Other important advantages attained by the invention and resulting from the fact that it makes it ssible to dis nse with balance weightsA or the electr e are the elect-rode, means resulting decrease in the size of the furnace and the weight of moving parts, with .resultingeconomies in o ri inal and operating costs, and possibility o much closer regulation, due to the elimination of weight in moving parts and a consequent decrease of work requisite for their acceleration. Because of the elimination of the counterbalancing weight, the net effect, in weight differential on the piston, is not nearly so great as when the weight of the electrode and its carrier frame is counterbalanced. Consequentl by setting the throttle valve for the conditions obtaining when the electrode is half` consumed, satisfactory operation over the whole range of adjustment is assured.

I claim:

1. In an electric furnace, the combination with a movable electrode carrier and an electrode mounted thereon, of a power cylinder for controlling the position of the carrier, a regulating device responsive to variations in the electrical power taken by the electrode for regulating flow of liquid under pressure to and from the c linder and a throttling device in the supp y line between the power cylinder and regulating device, said throttling device opening under pressure of liquid owing to the power cylinder and partially closing under pressure of liquid flowing from the power cylinder.

2. In. an electric furnace, the combination with a movable electrode carrier and an electrode mounted thereon, a power cylinder for controlling movement of the carrier, means for supplying liquid under pressure to the power cylinder against the weight of the carrier and electrode, a regulatin device for regulating flow of pressure me ium to and from the power cy inder, a throttling device in the supply| line between the power c linder and regulatin' device, said thrott ing device being opera le to close by liquid pressure from the power cylinder, and adjustable means for limiting closing movement of the throttling device. L

3. In an electric furnace, the combination with a movable electrode carrier and an electrode mounted thereon, of a power cylinder for controlling adjustment of the carrier, means for su plying ressure medium to the power cyliner, regu atin means for regulating flow of ressure me um to and from the power cylinder, a non-return valve in the su ply line between the re lating4 means an power c linder, and a justable means for limiting closing movement of the non-return valve.

4. In an electric furnace, a movable electrode, means controlling movement of said V governing controlling action of said contro means, means connecting said controlling means and said governing means and means comprising a check valve l in said connecting means for modifying thel con'trolling action of said control means.

5. In an electric furnace, a movable electrode, means controlling movement of said electrode, means overning controlling action of said controI means, means connecting said controlling means and said governing means a check valve in said connecting means for modifying the controlling action of said control means, and means for preventing complete closure of said valve.

In testimony whereof? I have hereunto subscribed m'y name at Zurich, Switzerland, this 18th day of Se tember, A. D. 1926.

GITTLIEB KELLER. 

